In the field of sportswear for racing, in which athletes struggle against each other to achieve a higher speed, various attempts have been made to decrease the resistance of the fabric itself to a flow of a fluid such as water and air, and the resistance of sportswear, etc., to a flow of a fluid by the design of the sportswear, etc. Making a fabric surface smooth has heretofore been known as means for decreasing the resistance of the fabric itself to water and air. For example, for a fabric used for racing swimwear, or the like, typical examples of the method of decreasing resistance to fluid such as water and air by smoothing the fabric surface include a method comprising pressing the fabric with a heat calendar roll or a hot plate, and a method comprising laminating a film, etc., to the fabric.
For example, Japanese Unexamined Patent Publication (Kokai) No. 7-279038 describes a fabric that is coated with a metallic thin film layer and subjected to resin treatment in addition to pressing with a heat calendar roll and that shows a very small standard deviation of surface roughness.
Japanese Unexamined Patent Publication (Kokai) Nos. 3-137203, 3-137204, 7-243104, 8-246209, 9-31721, 11-152610, and the like, describe a fabric the fluid resistance of which is decreased by providing the fabric with grooves and projections in a direction parallel to a fluid flow so that the fluid flow is made smooth.
Furthermore, Japanese Patent Publication No. 2711807, Japanese Unexamined Patent Publication (Kokai) No. 8-311751, Japanese Patent Publication No. 3283404, and the like, describe a method that combines a procedure of making a fabric water-repellent and a procedure of making the fabric non-water repellent so that the eddy resistance between fluid and the fabric is decreased.
Although all of the above conventional technologies consider the action of a fabric on a fluid, they do not consider the action of fluid exerted on a fabric, that is, they do not consider deformation of a fabric caused by fluid pressure. The following fabric has never been considered: a fabric designed to decrease a fluid resistance while a flow velocity of fluid in racing, in which athletes struggle against each other to get a higher speed, namely, a fabric deformation caused by fluid under a considerable pressure, is taken into consideration.
Furthermore, a method of decreasing resistance of fluid by making the fluid smooth in the direction parallel to the fluid flow has been known. However, when the fabric is provided with linear streaky unevenness parallel to the fluid flow, the size of an eddy generated increases because the path of the fluid proceeding on the fabric increases. Therefore, apprehensions about an increase in the fluid resistance are feared. The following fabric has never been found: a fabric designed to decrease fluid resistance that is exerted thereto in directions other than the fluid flow direction while the fabric is assumed to be actually worn and while wearer's motion in considerably random directions during wearer's practicing athletic sports, for example, wearer's hand motion during crawling in swimming is taken into consideration.